1. Field of the Invention
The present invention relates to a plasma processing apparatus and a plasma processing method for applying plasma processing such as etching to a substrate to be processed such as, for example a semiconductor wafer, and further relates to a focus ring and a focus ring component included in the plasma processing apparatus.
2. Description of the Related Art
Conventionally, a plasma processing apparatus performing plasma processing such as etching by using plasma generated by the application of high-frequency voltage has been in wide use in, for example, manufacturing processes and so on of microscopic electrical circuits in a semiconductor device. In such a plasma processing apparatus, to perform the plasma processing such as etching, a semiconductor wafer is placed in a process chamber whose inside is airtightly sealed, the high-frequency voltage is applied to generate plasma in the process chamber, and the plasma is made to act on the semiconductor wafer.
In some of such plasma processing apparatuses, a ring-shaped member called a focus ring is disposed to surround a periphery of the semiconductor wafer. This focus ring is made of a conductive material such as silicon and purposes of providing the focus ring are: to confine the plasma at the time of, for example, etching of an insulation film; to enable uniform high-quality processing not only in a center portion but also in a peripheral edge portion of the semiconductor wafer by reducing discontinuity of bias potential which is caused in a surface of the semiconductor wafer by an edge effect; and so on.
Further, to enhance processing uniformity in the peripheral edge portion of the semiconductor wafer by this focus ring, the present inventors have disclosed a focus ring whose upper surface of the focus ring has an inclined surface portion surrounding the semiconductor wafer and a horizontal surface portion formed continuously from and on an outer side of the inclined surface portion (see Japanese Patent Application Laid-open No. 2005-277369 (for example, FIGS. 1, 2).
In the invention disclosed in Japanese Patent Application Laid-open No. 2005-277369, owing to the specially designed upper surface of the focus ring, the tilt of an electric field in the peripheral edge portion of the semiconductor wafer is reduced, which enhances uniformity in etching, and a potential difference is generated between the peripheral edge of the semiconductor wafer and an inner circumferential surface of the focus ring, which prevents the plasma from entering an area under the peripheral edge portion of the semiconductor wafer.